Cyproterone acetate
Cyproterone acetate (CPA), sold alone under the brand name Androcur or with ethinylestradiol under the brand names Diane or Diane-35 among others, is an antiandrogen and progestin medication used in the treatment of androgen-dependent conditions such as acne, excessive body hair growth, early puberty, and prostate cancer, as a component of feminizing hormone therapy for transgender individuals, and in birth control pills. It is formulated and used both alone and in combination with an estrogen. CPA is taken by mouth one to three times per day.
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| Trade names | Androcur, Androcur Depot, Cyprostat, Siterone, others |
| Other names | SH-80714; SH-714; NSC-81430; 1α,2α-Methylene-6-chloro-17α-hydroxy-δ6-progesterone acetate; 1α,2α-Methylene-6-chloro-17α-hydroxypregna-4,6-diene-3,20-dione acetate |
| AHFS/Drugs.com | Micromedex Detailed Consumer Information |
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| Routes of administration | By mouth, intramuscular injection |
| Drug class | Steroidal antiandrogen; Progestogen; Progestin; Progestogen ester; Antigonadotropin |
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| Bioavailability | Oral: 68–100% |
| Protein binding | Albumin: 93% Free: 7% |
| Metabolism | Hepatic (CYP3A4) |
| Metabolites | • 15β-OH-CPA (major) • Cyproterone (minor) • Acetic acid (minor) |
| Elimination half-life | Oral: 1.6–4.3 days IM: 3–4.3 days |
| Excretion | Feces: 70% Urine: 30% |
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| ECHA InfoCard | 100.006.409 |
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| Formula | C24H29ClO4 |
| Molar mass | 416.94 g·mol−1 |
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| Melting point | 200 to 201 °C (392 to 394 °F) |
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Common side effects of high-dose CPA in men include gynecomastia (breast development) and feminization. In both men and women, possible side effects of CPA include low sex hormone levels, reversible infertility, sexual dysfunction, fatigue, depression, weight gain, and elevated liver enzymes. At very high doses in older individuals, significant cardiovascular complications can occur. Rare but serious adverse reactions of CPA include blood clots, liver damage and brain tumors. CPA can also cause adrenal insufficiency as a withdrawal effect if it is discontinued abruptly from a high dosage. CPA blocks the effects of androgens such as testosterone in the body, which it does by preventing them from interacting with their biological target, the androgen receptor (AR), and by reducing their production by the gonads, hence their concentrations in the body. In addition, it has progesterone-like effects by activating the progesterone receptor (PR). It can also produce weak cortisol-like effects at very high doses.
CPA was discovered in 1961. It was originally developed as a progestin. In 1965, the antiandrogenic effects of CPA were discovered. CPA was first marketed, as an antiandrogen, in 1973, and was the first antiandrogen to be introduced for medical use. A few years later, in 1978, CPA was introduced as a progestin in a birth control pill. It has been described as a "first-generation" progestin and as the prototypical antiandrogen. CPA is available widely throughout the world. An exception is the United States, where it is not approved for use.